Mechanisms controlling RHO gtpase activation during cytokinesis

The National Cancer Institute awarded the University of Oregon $100,228 under the Cancer Research Manpower program (CFDA 93.398) on December 1, 2026, to support research training in mechanisms controlling RHO GTPase activation during cytokinesis.

The award funds a doctoral trainee's research investigating how the proteins ECT2 and CYK4 regulate RHO GTPase activity and spatial organization during cell division. The trainee will test three specific aims: examining whether ECT2 exhibits positive feedback through dual binding to RHO (Aim 1), determining how CYK4 modulates ECT2 membrane localization and activity (Aim 2), and defining the role of CYK4 oligomerization in controlling these functions (Aim 3). The research develops a novel platform for biochemically reconstituting RHO GTPase activation on supported lipid bilayers combined with single-molecule total internal reflection fluorescence microscopy, providing training in enzyme kinetics and quantitative image analysis to prepare the trainee for independent investigator status.

Performance occurs in Eugene, Oregon. The project period extends from December 1, 2026, through June 30, 2029. This assistance type is a project grant supporting biomedical training opportunities for individuals pursuing careers in basic research relevant to the National Cancer Program.

Abstract

(project summary) following genome replication, eukaryotic cells divide through a process called cytokinesis. Phylogenetic and computational structural analysis indicate that cytokinesis is regulated by a small set of highly conserved proteins: rhoa gtpase, ECT2, and CYK4 of the centralspindlin complex (CC). During cytokinesis, active rhoa gtpases organize into spatial patterns on the plasma membrane that concentrate at the cleavage furrow. A combination of positive and negative feedback loops are hypothesized to control these patterns by dynamically toggling rhoa between the active GTP-bound state and the inactive GDP-bound state. Essential for rhoa spatial organization are the evolutionarily conserved guanine nucleotide exchange factor (GEF), ECT2, and a gtpase activating protein (GAP), CYK4. Deciphering the interactions between ECT2 and CYK4 is critical for understanding how the activity of membrane anchored rhoa is regulated during cytokinesis. Understanding this mechanism is broadly important for determining how metazoans regulate cell division with high fidelity. To fill this GAP in knowledge, the applicant will test the hypothesis that ECT2 exhibits positive feedback based on dual binding to rhoa (aim 1). In parallel, they will determine how CYK4 modulates ECT2 membrane localization and activity (aim 2), and the role CYK4 oligomerization serves in controlling these functions (aim 3). This project offers a unique opportunity for the applicant to develop a novel platform for biochemically reconstituting rhoa gtpase activation on supported lipid bilayers. Combined with single molecule tirf microscopy, the applicant will gain modern skills in enzyme kinetics and quantitative image analysis. This training will provide crucial scientific growth needed for the applicant to become an independent investigator, including improved communication, writing, mentorship, and leadership skills. Overall, determining how ECT2 and CYK4 regulate rhoa activation is a fantastic opportunity for the applicant to build research independence leveraging hansen lab expertise in membrane signaling to pursue an impactful new research direction.